Finasteride, not tamsulosin, increases severity of erectile dysfunction and decreases testosterone levels in men with benign prostatic hyperplasia

Horm Mol Biol Clin Investig. 2015 Sep;23(3):85-96. doi: 10.1515/hmbci-2015-0015.


Background: 5α-reductase inhibitors (5α-RIs) (finasteride and dutasteride) have been proven useful in treatment of lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia (BPH). However, these inhibitors exert undesirable sexual side effects and, in some cases, these effects are persistent. There is considerable disagreement with regard to whether the adverse side effects resolve with continuous treatment.

Aim: To investigate the long-term adverse effects of finasteride treatment in men with BPH on erectile function and to compare these adverse effects in men treated with the α1-adrenergic receptor blocker, tamsolusin.

Methods: In this retrospective registry study, a cohort of 470 men aged between 47 and 68 years (mean 57.78±4.81) were treated with finasteride (5 mg/day). A second cohort of 230 men aged between 52 and 72 years (mean 62.62±4.65) were treated with tamsulosin (0.4 mg). All men were followed up for 45 months. At intervals of 3 months and at each visit, plasma testosterone (T) levels and the international index of erectile function (IIEF-EF) questionnaire scores were determined.

Results: Long-term treatment with finasteride therapy is associated with worsening of erectile dysfunction (ED) as shown by the significant decrease in the IIEF-EF scores in men treated with finasteride. No worsening of ED was observed in men treated with tamsulosin. The increase in ED due to finasteride did not resolve with continued treatment with finasteride. Most importantly, long-term finasteride therapy resulted in reduction in total T levels, contributing to a state of hypogonadism. On the contrary, no changes in T levels were noted in men treated with tamsolusin.

Conclusion: Our findings suggest that in men with BPH, long-term finasteride therapy but not tamsulosin results in worsening of ED and reduces total T concentrations. Clinicians are urged to discuss the impact of 5α-RIs therapy on sexual function with their patients before commencing this therapy.

MeSH terms

  • Aged
  • Cohort Studies
  • Erectile Dysfunction / chemically induced*
  • Finasteride / adverse effects*
  • Finasteride / metabolism
  • Humans
  • Male
  • Middle Aged
  • Prostatic Hyperplasia / drug therapy*
  • Sulfonamides / therapeutic use
  • Tamsulosin
  • Testosterone / metabolism*
  • Urological Agents / adverse effects*
  • Urological Agents / metabolism


  • Sulfonamides
  • Urological Agents
  • Testosterone
  • Finasteride
  • Tamsulosin